Burner control



Nov. 17, 1942. R W, JQHNSQN 2,302,223

BURNER CONTROL FilecIl Nov. 30, 1959 3 Sheets-Sheet 1 TTORNEY Nov. 17, 1942. R W 4JQHN5QN 2,302,223

BURNER CONTROL l Filed Nov. 30, 1939 3 Shee'ts-Sheet 2 lillllmllllll ATTORNEY Patented Nov. 17, 1942 UNITED STATES PATENT olFlcE 11 Claims.

This invention relates to an improvement in controls, especially designed and adapted for use with heaters of the type wherein the heater is fired by a liquid fuel or oil burner.V

A typical installation is in connection with a hot air furnace employing a pot type burner, or its equivalent, to which oil or liquid fuel is fed by gravity under the control of the metering valve. Air to support combustion is fed to the combustion chamber, usually by means of an electric motor-driven fan. 1

One of the objects of the present invention is to provide a control of this character, which exercises very effective regulation over the opera- 15 manner in which the valve-operating lever is tion of the burner, in that it provides for a three stage burner operation, the metering valve being positioned under the automatic regulation of the control in either low re or pilot position, or in a position to provide for a moderate or intermediate ame, or in position for a high or maximum fire flame. The control is responsive in its action to the regulation of a room thermol stat, and it not only meters the flow of the liquid fuel to the burner, but also provides a means for coordinating therewith the control for the supply of air to the combustion chamber. In carrying out this purpose, the control regulates the operation of the electric motor which drives the pot fan, and also has a movable lever arm adapted to be connected to and to provide controlled motion for draft regulating dampers.

A still further object of the invention is to provide a control having these advantages and capacities, and which is very simple and compact in its construction, reliable and effective in operation, and easy and comparatively inexpensive to manufacture and install.

Other objects and advantages reside in certain novel features of the construction, arrangement, and combination of parts which will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to the accompanying drawings forming a part of this specification, and in which:

Figure 1 is a view'partly in side elevation and partly in longitudinal and vertical cross section, showing a control device embodying the present invention. o

Figure 2 is a fragmentary view taken in transverse vvertical cross section on line 2-2 of Figure 4.

Figure 3 is a fragmentary view in vertical cross section, illustrating the metering valve, its high fire stop, and associated structure.

Figure 4 is a view of the oil control in top plan 5 5 with the Shen-nre cover of the control casing removed.

Figure 5 is a fragmentary view partly in side elevation and partly in longitudinal vertical section, showing the oppositel side of the control from that illustrated in Figure 1.

section, taken on line 1 1 of Figure 6.

Figure 8 is a fragmentary view in longitudinal vertical cross section, taken on line 8--8 of Figure 6.

Figure 9 is a view in elevation illustrating the interlinked with the damper "in the air supply conduit; and Y Figure 10 is a diagram of the electrical circuits of the control.

Referring to the drawings, it will be seen that the furnace control device embodying the present invention comprises a main casing I0 having a main liquid supply chamber Il therein. Liquid fuel is supplied tothe chamber Il, and a' constant level is maintained therein by mechanism which forms per se no part of the present invention, and which is fully disclosed in United States LettersPatent No. 2,068,138, granted January 19, 1937, to Roy `W.-Johnson. The liquid supply chamber Il is provided with one or more outlets I 3 1 (see Figure 3) which lead to thev burner. The burner is usually of the pot type, and is not shown. The flow of liquid through each of the outlets I3 is regulated by means of a tubular metering valve I4 mounted for rectilinear up and down movement in a tubular valve guide I5', biased to'open position by means oi a spring 16, and further guided by a radially projecting pin Il, which works in a vertical guide slot in the guide tube I5. The construction of this metering valve I4, and also of its high fire stop I9 and low fire stop 20, except in the 'particulars which will be hereinafter described, is fully disclosed and claimed in the application of Roy W. Johnson, for Interchangeable metering valve control, led June 2k3, 1938, Serial No. 215,336, issued Junev 3, 1941, as Patent No. 2,244,161. i

The upper end of the metering valve I4 pro- 'jects up through an opening provided in the cover frame I0 of the casing 'I 0, and also through an opening provided therefor in the base plate 2l of the casing of the control mechanism. The base plate 2l is fastened in position on the cover frame of the` main casing. A control `cover 22 Figure 6 is a view inhorlzontal cross section,

of shell-like form coacts with the base plate 2|, and with the uprights I5 integrally formed with the ends of the base 2|, to complete the enclosure of the control parts. Screws or other suitable fastening'devices are employed for securing the base plate 2| in position, and for releasably securing the control casing cover 22 assembled with the base plate 2|. g

A Apair of transversely spaced vertical bracket plates 25 are integrally formed with the base plate 2| adjacent one end thereof. A valve-operating lever 26, which may be constituted ofsheet metal, is formed at one end with a pair of spaced and apertured ears 21. A pivot pin 28, supported on the bracket plates 25, extends through apertures of the ears 21 to pivotally support or fulcrum the valve-operating lever 26 at one of its ends. The end of the lever 26 opposite its fulcrum is formed with a lateral extension 26', which overlies the upper end of the metering valve I 4, and also overlies the low fire stop 20, so that when the lever 26 is allowed to swing downwardly, its extension v, 26' presses against a boss I4' formed on the upper end of the metering valve I4, and so causes the metering valve to move or shift to low or pilot lire position against the action of its spring I6. When the lever 26 has shifted the valve I3 to low ilre position, the lever comes into engagement with the low fire stop 20, and any further downward movement of the lever 26 is prevented.

A torsion coil spring 24 encircles a portion of the pivot in 29 located between the ears 21 of the valve-operating lever 26, and has extended ends 24', one end 24' bearing down upon the valve-operating lever, Vand the other end abutting the base plate 2|. The spring 24 is thus tensioned to swing the end of the valve-operating lever 26, engageable with metering vvalve I4, downwardly. The torsion spring 24 is stronger than the valve spring I6 so that when the torsion spring 24 is free to act, it overcomes the effect of the spring I6.

'I'he present invention proposes to provide a plurality of electric power elements to impart opening movement to the valve-operating lever 26, and proposes to energize and deenergize the power elements under control of the room thermostat, so that depending upon the demands of the room thermostat the valve I4 will occupy either high or low, or intermediate nre position.

The electric power element, which is employed for shifting the valve-operating lever to an intermediate fire position, takes the form of a bimetallic leaf, designated at 29. 'Ihe leaf 29 has one end fastened, as by screws 29', to a bearing pad'25' provided therefor on the base 2|. The.,

opposite end of the leaf 29 underlies an angular lug 30, which is formed integral with the valveoperating` lever 26. An electric heating element 3| is clipped, or otherwise suitably secured, to the underside of an intermediate portion of .the bi-metallic leaf 29, and when it is energized, and heats up, it causes the leaf 29 to flex upwardly. The free end of the leaf 29 when so flexed presses up against the underside of a bearing button 30' iixed to the horizontal portion of the angular lug 30, and consequently shifts the valve-operating lever 26 upwardly, and does this to such extent as to permit the valve spring I 6 to move the valve to intermediate fire position. A stop screw 32 is mounted on the base plate, and is arranged so that a portion ofits head overlies the free end of the bi-metallic leaf, and will engage such end of the leaf and arrest further upward movement thereof when the valve-operating lever, and consequently the metering valve I4, are in intermediate ilre position.

For the purpose of shifting the valve-operating lever 26, and consequently the metering valve I4, to high ilre position, the invention proposes an electro-power element in the form of a bellows or expansible chamber 35. The cylindrical casing of the bellows 35 is iixedly supported on a. bellows bracket 4I which isin turn secured to the bracket plates 25 and the base 2|. The vertical portion of bellows bracket 4| has an opening in which one end portion of the cylindrical casing of the bellows is fitted, and such end portion of the bellows casing has an integral outwardly directed annular flange 35 which overlaps the margin of the opening in the bellows bracket 4I and is secured thereto by screws 424 (see Figures 2, 6, and 7). A washer 43 is interposed between the ange 35' and bellows. bracket 4I. The bellows 35 is lled with an expansible liquid or fluid. An electric heating element 36 energized and de-energized under the influence of the room thermostat, and, acting when energized to cause the fluid in the bellows to expand, surrounds the metal casing of the bellows. The electric heating element is Ipreferably in the form of a fine wire of zigzag form embedded in thin sheets of mica which are wrapped around and clamped snugly up against'the outer wall of its bellows casing. When the fluid in the bellows 35 is expanded its bellows tip 31 moves outwardly, and due to its engagement with the bearing screw 38 Vof bell-crank lever 39 rocks the bell-crank lever in a counter-clockwise direction, as viewed in Figure 8. The lever 39 is also pivotally mounted on the pivot pin 28 alongside of the lever 26, and its lower arm 39' is at and curved laterally and underlies the valve lever 26. A torsion coil spring 40, which has its coils encircling a portion of the pin 28, has one end bearing against the base plate and its opposite end bearing down on the arm 39 of the lever 39, so as to swing the arm 39 downwardly away from the lever 26, except when the fluid in the bellows is expanded. l The bellows 35, when the fluid in it is expanded, acts through lever 39 to swing valve-operating lever 26 upwardly away from the valve I4 to such extent as to allow the valve spring I6 to move the valve I4 to full open or high fire position. High ilre stop I9 engages valve pin I1 to limit the extent to which valve I4 may open. The lever 26 is free to continue to travel upwardly away from the valve I4 after the valve is fully open, and this is desired in many instances. For example, it may be desired or required, where such movement of the valve-operating lever 26 is employed, to regulate the action of a damper for controlling the air supply to the burner.

However, while this over travel of the lever 26 away from the valve I4 is desirable in some instances, it is important that its return movement under the control of the bellows 35 be promptly transmitted to the valve I4 to effect its return to intermediate fire positie-n while leaving the shifting of the valve I4 from intermediate ilre position to low or pilot fire position under the complete control of the bimetallic leaf 29. To carry out these purposes and effect the action desired the valve-operating lever 26 not only has its extension 26 cooperable with the boss I4' of the metering valve I4, but also is interconnected' vagainst the action of metering valve I4 to fully closed or shut-off poand 60h integrally connected atone end by a bight portion.

Adjacent its bight portion the clip is frictionally and securely engaged in an annular groove provided in the upper end of the button 30 fastened to the angular lug 38 of the lever 26. Adjacent their free ends the spring v arms 60a and 60h straddle and frictionally engage the friction sleeve 6 I Y The friction sleeve 6I overlies a portion of the upper end of the valve I4 to one side of the boss I4 and extension 26' of the lever 26, and it may be conveniently constrained to vertical sliding movement by slidably fitting it on a manually operable shut-off pin 62 with which the control is also provided. v

The portion of the friction sleeve 6I which the clip 60 engages is constituted to frictionally engage the clip 69 and yet at the proper .time permit the desired slippage of the clip along such portion ofthe sleeve, but the lower end of the sleeve 6I (which is not engaged by the clip 69 at any time) is externally threaded. An interchamber. The glass envelope of this switch is at which time the stop disk 63 of the sleeve 6I engages the top of stop screw v32 to arrest furA ther downward movement of thedisk 63 and its sleeve 6I. The lever 39 may then continue to move downwardly, and the bimetallic leaf 29 takes over the control of lever 26, and if theleaf 29 permits further downward movement of lever 26 then clip 69 slips downwardly on the friction sleeve 6I.

The terminal board 45 is of Bakelite or other insulating material, and of general plate-like form, and-is supported in the control casing on the bracket plates 25 and on vertical posts 46 provided therefor. Screws 4'I4 secure one end of the terminal board to the posts. The opposite end of the terminal board has a depending lug'- like and integral extension 48, which rests on the horizontal flange of the bellows bracket 4I, and is fastened in position by screws 49, which also secure the bellows bracket 4I to plates 25.

A mercury switch 50 is provided for controlling the operation of the electric motorfor the pot fan or the fan that supplies air to the combustion supported in a clip 5Icarried at the outer end of a short rock arm 52. The other end of this 'rock arm 52 is pivotally mounted on a pivot pin 53 supported in 'a sleeve-like bearing formed nally threaded stop disk 63 is threadedly engaged with the lower portion of the sleeve so as to be adjustable therealong. The stop disk 63 is adjusted at the factory, and to preclude tampering with the adjustment in the field, it may be permanently secured in its final adjustment by soldering'.

A snap ring 60' is snapped into an annular groove provided in the upper end of the sleeve 6I to prevent the arms 60a. and 69h of the clip 60 from riding olf the upper end of the sleeve 6I.

The shut-off pin 62 is supported by means of a two-part casing or .cylinder 64 suitably mounted on the terminal board 45. The sections of the casing 64 are threadedly interconnected and held in any selected adjustment by a friction spring 64'.. A spring 62 encircles the pin 62 within the casing 64, and has its lower end abutting the lower section of the casing 64 and its upper end abutting a collar 62a integral with pin 62. A

button 62h integral with the pin 62 projects above the casing 64. Whenthe button 62b is depressed the shut-'off pin moves downwardly spring 62' to punch the sition.-

is heated up, and the lever 39 swings lever 26 ,upwardlyjthe valve I4, levers 26 and 29, wire clip 60, and sleeve 6I all move upwardly together .until the valve I4 reaches high re position whereupon its further upward movement is ar. rested by high fire stop I9. At about the same time the upper end of the sleeve 6I engages the lower end of casing 64, and its further upward movement is stopped. The levers 39 and 26 and wire clip 69 may continue to move upwardly, the wire clip 60 slipping-along the friction sleeve 6I. But when the electric heating element 36 is deenergized,` and the bellows cools off, and levers 39 and 26 start to swing back toward the valve I4, the wire clip 60 at once moves the sleeve 6I downwardly, and as its lower end is engaged with the valve I4 the valve is also moved toward its seat until it comes to intermediate fire position, 75

integral with the under side of the terminal board. The switch is interlocked with the control mechanism for the metering valve I4 so that it will be in its open position whenthe metering valve is in low fire or pilot position, or will be closed in the other positions of the valve. For this purpose, and for other purposes which will be hereinafter described, the valve-operating 1ever 26 has an extension 56 spot-welded thereto. A vertical lug 5'I is formed integralwith this extension, and is pivotally connected tothe lower end of a link 58.

The upper end of the link 58 is provided with a slot 58. A headed pin 52 extends through this slot-'58' and is fastened to rock arm 52 to `provide a lost motiony connection between the upper end of the link 58 and the rock arm 52. A mousetrap spring 59 is interposed between the link 58 and rock arm 52, andxhas the arms diverging from its' coiled bight portion secured vrespectively to the link 58 and rock arm 52.

essary to provide some means to allow the lever 26 to continue to swing after the mercury switch 5l! has been tilted to closed position, and this necessity is very advantageously satisfied by the pin and slot connection 52', 58', and the spring 59.

. When either the bi-metallic leaf 29 or bellowsactuated lever 39 swing the valve-operating lever 26 upwardly, the link 58 is thrust upwardly and the spring 59 transmits the upward movement of the link 58 to the rock arm 52 to tilt the mercury switchto closed position. If the lever 26 continues to move upwardly, the spring 59 yields and the link-58 shifts relative to the rock arm 52, the slot 58' of the link 58 sliding along the red, white, and blue contacts 1I, 12, and 13.

White contact 13 is connected by wire 14 with binding post numbered I on the terminal board 45; red contact 1I is connected by wire 15 with binding post numbered 2 on board 45; and blue contact 12 is connected by wire 16 with binding post numbered 4. The bi-metallic element of the room thermostat carries the movable con- -tact 1|' cooperable with red contact 1I, and also has an insulating button 10a engageable with the movable blade contact 13' mounted on and electrically connected with the white contact 13 and biased to engage an extension 12' of blue contact 12. electrically connects the bi-metallic element 10' and its movable contact 1I' with the white contact 13.

Wire 11 connects binding post numbered 4 with one terminal of the heating element 3| of the bi-metallic leaf 29. The other terminal of element 3| is connected by wire 18 to binding post numbered 3. Wire 19 connects binding post numbered 2 with one terminal of bellows heater 36. The other terminal of the heater 36 is connected by wires 80 and 'I8 to the binding post numbered 3.

The low voltage circuits of the control device are energized from the line through a step down transformer shown diagrammatically at 8|, one of the terminals of the secondary coil of transformer 8| being connected by wire 82 to binding post I, and the other by wire 33 to binding post 3.

In Figure 10 the pot fan motor, which supplies air to the pot or combustion chamber of the burner, is designated diagrammatically at 85. One terminal of the motor is connected directly to one side oi the line by wire 86. The other terminal of the motor is connected by wire 81 to binding post v8 of the terminal board. Wire 83 connects binding post 8 to one of the electrodes of the mercury switch`50. The other electrode of this mercury switch 50 is connected by wire 89 to binding post 1, which in turn connects by wire 90 to the other side of the line. It is obvious that when the body of mercury in the mercury switch bridges the electrodes, the circuit through the pot fan motor is completed, and that when- A iiexible conductor 13a also f terminal of the secondary oi the transionner 8|, through wire 82, binding post I, wire 14, white v contact 13, movable blade contact 13', extension the mercury switch is tilted to leave a gap between the electrodes, the circuit through lthe pot fan motor is broken. f

When the bi-metallic element 10' of the room thermostat 10 is in the position shown in Figure l0, then the room thermostat 10 is satised and the circuit through both the heaters 3| and 36 is broken, and both are de-energized so that the metering valve is in its pilot or low re position.v

If the temperature conditions to which the room thermostat 10 is subjected are such to cause the bi-metallic element 10 to move toward the left, as viewed in Figure 10, then the movable blade contact 13' will engage the extension contact 12' of blue contact 12 and current will fiowlfrom one contact 12', blue contact 12, wire 16, binding post 4, wire 11, electric heating element 3|, wire 18, binding post 3, and wire 83, back to the other terminal oi' the secondary of the transformer. As the heating element 3| heats up, it iexes its thermostatic leaf 29 upwardly to raise the metering valve to intermediate re position.

If the temperature conditions in the environment of the room thermostat are such as to cause its bi-metallic element 10' to continue to move to the left until its movable contact 1I engages the red contact 1|, then the current will :dow from one terminal of the secondary oi the transformer 8|, through wire 82, binding post I, wire 14, white contact 13, ilexible conductor 13a, bl-metallic element 10', movable contact 1|', red contact 1|, wire 15, binding post 2, wire 19, electric heating element 36 oi. bellows 35, wire 80, and wire 13 to binding post 3, and then through wire 83 to the other terminal of the secondary of the transformer. The heater 36 heats up the expansible or -volatile fluid or liquid in the bellows 35, and

. thereby shifts the lever 39 to further raise the valve-operating levers 26 and allow the valve I4 to fully open or come to high fire position.

As previously indicated, Supply of air to the combustion chamber is regulated or coordinated with the supply of fuel to the burner, and for this purpose the extension 5B of the valve-operating lever projects out beyond the control casing, and has a yieldable connection consisting of a spring 9| and nut 92 to the upper end oi' a rod 93. The lower end of this rod extends through an opening provided therefor in the short arm of a lever 94. The details oi the damper form no part of this invention and are more fully described and claimed in United States Patent No. 2,251,055, issued July 29, 1941, on application of David J. Howard and Samson J.'Johnson. Below the short arm of the lever a washer and cotter pin 96 are combined with the rod to provide an abutment for bearing points 91 formed in the short arm oi the lever. A spring 98 bears down on the short arm of the lever and abuts a collar 99 on the rod. This structure provides a desirable type of yieldable operable connection between the rod and the lever 94. The lever 94 is pivoted or iulcrumed as at |00 on a mounting bracket I0| supported on the conduit |02 between the fan and the pot or combustion chamber of the burner. This conduit |02 has an opening |04 in its under side. Supported for rotation on the conduit, and in controlling relation to the opening |04, is a damper |05. The damper is fixed on a rotatably supporting shaft |06 mounted in any suitable way on the conduit |02. A crank arm |01 is secured by a set screw |00 to the shaft |06. The outer end of this crank arm is pivotally connected to the lower end of the link |09, and the opposite end of this link is pivotally connected to the outer end of the long arm of the lever 94. With this or so'me equivalent system of linkage and leverag'e, the motion of the valveoperating lever, or of its extension, is multiplied suiliciently to give a different position to the damper for each position of the metering valve. When the metering valve is in its pilot or low iire position, the damper is positioned in the full line shown in Figure 10, blocking the passage through conduit from the fan to the burner but allowing a natural draft from the atmosphere through a .portion oi' the opening |04 to the combustion s the flow of fuel asoaaas chamber. When the metering valve is in an intermediate firing position, the damper i" isangled so as to partially block conduit |02. However, when the metering valve is in lits high firing position, the damper lill closes the opening |04 and leaves the conduit |02 unobstructed so that the entire draft'set up by the fan is delivered to ,the combustion chamber.

While I have shown and described one construction in which the invention may be advantageously embodied, it is`to be understood that the construction shown has been selected merely for the purpose of illustration or example, and

that various changes in the size, shape, and arrangement of parts may be made without departing from the spirit of the invntion or the scope of the subjoined claims.

I claim:

1. A control for oil burners comprising avmetering valve biased to open position and regulating to the burner, a valve-operating lever engageable with the valve to move it toward closed position when swung in one direction and to allow it to open when swung in the opposite direction, a bi-metallic leaf flexing when heated to swing the lever` in a direction to allow the valve 1 to open, means for limiting the extent to which said leaf may flex when heated, an electric heating element for heating the leaf, a bellows having an expansible fluid therein, a connection between the bellows and said lever operable when the fluid in the bellows is heated to swing the lever farther away from the valve, an electric element for heating the fluid in the bellows, and thermostatic means for regulating the energization and de- 3 energization of said electric heating elements.

2. A control for oil burners comprising a. metering valve biased to open position and regulating the flow 0f oil to the burner, -a main valveoperating lever having one end'fulcrumed and having its other end overlying the metering valve and acting when swung in one direction to force the valve toward closed position, and when swung in the other direction to allow the valve to open, a thermostatic leaf flexed when heated and engageable with the lever to shift the lever in -a direction to allow the valve to open, anelectric heating element for said thermostatic leaf, means for limiting the extent to which said leaf may flex under the influence of heat, a bellows containing an expansible fluid and having a bellows tip moved outwardly when the fluid is heated, an auxiliary valve-operating lever engaged by said bellows tip and having an arm underlying the main operating lever and engageable therewith to shift the same farther away from thervalve, an electric heating element surrounding the bellows, and a room thermostat for controlling the energization of said electric heating elements.

3. A control for oil burners comprising a metering valve biased to open position and regulating the flow of fluid to the burner, a main valve-operating lever overlying the valve and engageable therewith to move the valve toward closed position when swung in one direction and to allow the valve to open when swung in the other direction, said lever having an angular lug projecting from one side thereof, abi-metallic leaf flexed when heated Aand engageable with said lug to move the lever away from the valve, an electric heating element for said bi-metallic leaf, a stop for limiting the extent to which-the leaf may flex, an auxiliary valve-operating lever lever and effective when swung in one direction to move the main valve operating lever to a position to allow the valve to fullyopen, a bellows containing an expansible fluid and having abellows tip engageable with the auxiliary valveoperating lever, an electric heating element for heating the fluid in the bellows, and thermostatic means for regulating the energization of said heating elements.

ff. A control for oil burners'comprising a m tering valve for regulating the flow of fuel to the burner, said metering valve being biased to open position, a valve operating lever engageable with the valve to move it toward closed position when swung in one direction and to allow it to open when swungin the opposite direction. a bi-metallic leaf operable when heated to swing the lever in a direction to allow 'the valve to open, adjustable means for limiting the extent to which the leaf may flex when heated while permitting the lever to further swing in said direction. an electric heating element for heating the leaf, and thermostatic means for regulating "the energization and de-energization of said elecating lever overlying `the valve and engageable therewith to move the valve toward closed position when swung in one direction and to allow the valve to open when swung in the other direction, an electro-responsive power element cooperable with the lever to move the same in the di- 5 rection to allow the valve to open, a one-way friction drive between said lever and said-valve operable to impart closing movement to the valve when the lever is swung in one direction, stop means to limit the extent to which said friction drive may move the valve toward closed position, and thermostatic means for controlling the action of said electro-responsive element.

6. A control for oil burners comprising a metering valve biased to open position and regulat- 4., ing the flow of fluid to the burner, a main valveoperating lever overlying the valve and engageable therewith to move the valve toward closed position when swung in one direction and to allow the valve to open when swung in the other direction, an auxiliary valve-operating lever having an arm underlying the main operating lever and effective when swung in one direction to move the main operating lever to a'position to allow the valve to open, a bellows containing an expansible uid and having a bellows tip engageable with another arm of said auxiliary arm operating lever, and thermostatic means for regulating the expansion and contraction of the fluid in said bellows.

'7. A control for oil burners comprising a metering valve biased to open position andregulating the flow of fluid to the burner, a main valveoperating lever overlying the valve and engageable therewith to move the valve toward closed position when swung in one direction and to allow the valve to open when swung in the other direction, thermostatically controlled means cooperable with the lever for swinging the same in a direction to allow the valve to open, means for limiting the extent towhich said thermostatically controlled means may swing the lever in a direction to allow the valve to open. an auxiliary valve-operating lever having an arm underlying the main valve-operating lever and effechaving an arm underlying the main operating tive when swung in one direction to move the main valve-operating lever to a position to allow the valve to fully open, and thermostatically controlled means for actuating said auxiliary valve-operating lever.

8^. A control for oil burners comprising a metering valve biased to open position and regulating the flow of oil to the burner, a high fire stop cooperable with the valve to limit the opening movement thereof, an operating lever overlying and engageable with the valve to move the valve toward closed position when swung in one direction and to allow the valve to open when swung in the other direction. a low re stop underlying the lever and limiting the extent to which the lever may swing to close the valve. two electroresponsive power elements operatively connected with the lever for swinging the lever in a direction to allow the valve to open when said electro-responsive power elements are energized, means for limiting the extent to which one of said electro-responsiveA power elements may swing the lever whereby to cause the valve to occupy a position intermediate its high and low fire positions when said last named electro-responsive power elementis energized, and thermo-- statically controlled means for regulating the energization of said electro-responsive power elements.

9. A control for oil burners comprising a metering valve biased to open position and regulating the flow of fuel to the burner, a valveoperating lever engageable with the valve to move it toward closed position when swung in one direction and to allow it to open when swung in the opposite direction. a bi-metallic leaf exing when heated and co-acting with the lever to swing the lever in a direction to allow the valve to open, means for limiting the extent to which said leaf may flex when heated. an electric heating element for heating the leaf, a bellows having the expansible fluid therein, a connection between the bellows and said lever operable when the fluid in the bellows is heated to swing the lever farther away from the valve, a one-way friction drive between said lever and said valve operable to impart closing movement to the valve when the lever is swung toward the valve and including frictionally interengaged elements one connected to the lever and the other engageable with the valve, the element engageable with the valve also being engageable with said means to limit the extent to which it may move the valve toward closed position, and theremostatic means for regulating the energization and deenergization of said electric heating elements.

10. A control for oil burners of the type having an electric motor-driven fan for supplying air to the combustion chamber of the burner and a metering valve biased to open position and regulating the flow of oil to the burner and comprising a high re stop cooperable with the valve to limit the opening movement thereof. an operating lever overlying and engageable with the valve to move the valve toward closed position when swung in one direction and to allow the valve to open when swung in the other direction, a low fire stop underlying the lever and limiting the extent to which the lever may swing to close the valve, an electrically energized power element cooperable with the lever to swing the same away from the lowire` stop to allow the valve to open, a mercury switch for regulating the supply of electric current to said motor, a tiltable support for said switch, a link having one end pivotally connected with the lever, and a spring-tensioned lost motion connection between the other end of the lik and the tiltable support,

11. A control for oil burners comprising a metering valve biased to open position and regulating the ow of oil to the burner, a high re stop cooperable with the valve to limit the opening movement thereof, an operating lever overlying and engageable with the valve to move the valve toward closed position when swung in one direction and to allow the valve to open when swung in the other direction, a low fire stop underlying the lever and limiting the extent to which the lever may swing to close the valve, two electroresponsive power elements operatively connected with the lever for swinging the lever in a direction to allow the valve to open when said electro-responsive power elements are energized, means for limiting the extent to which one of said electro-responsive power elements may swing the lever whereby to cause the valve to occupy a position intermediate its high and low fire positions when said last named electro-responsive power element is energized, a one-way friction drive between said lever and said valve operable to impart closing movement to the valve when the lever is swung toward the valve and having its valve-engaging element cooperable with said means to limit the extent to which said friction drive may move the valve toward closed position, and thermostatically controlled means for regulating the energization of said electroresponsive power elements.

ROY W. JOHNSON. 

